Method for producing an adhesive closing element

ABSTRACT

A method for producing an adhesive closing element having a plurality of hook elements formed as a single piece with a support. The hook elements are rod-shaped and have enlargements at their ends. A thermoplastic synthetic material is fed into the gap between two moveable tools in a plastic or liquid state. The tools are driven such that a support is formed in the gap and displaced in a direction of conveyance. The hook elements are formed by forming elements acting on the gap. The hook elements are formed on both sides of tile support by the forming elements that are active on both sides of the gap.

FIELD OF THE INVENTION

The present invention relates to a method for producing an adhesiveclosing element with a plurality of hook elements that form a singlepiece with a support. The hook elements are in the form of rods havingenlargements on the ends. A thermoplastic synthetic resin in a plasticor fluid state is fed into the gap between movable tools The tools aredriven in such a manner that the support is formed in the gap and isconveyed in a direction of conveyance, whereby book elements are formedon both sides of the support by forming elements agog on both sides onthe gap.

BACKGROUND OF THE INVENTION

A method of forming adhesive closing elements in disclosed inpublication WO 95/01863. The execution of this method takes place in adisadvantageously costly manner, when finely structured hook elementsare to be produced in great number and are arranged on the support incorrespondingly high packing density. As a result, the production of theforming elements, which form the hook elements, is extraordinarilycostly.

SUMMARY OF THE INVENTION

Objects of the present invention are to provide a method facilitatinglow-cost production of adhesive closing elements with finely structuredhook elements arranged in high packing density.

These objects are attained according to the present invention byarranging hollow spaces passing through a first screen and a secondscreen on the interior of the first screen for forming elements. Thehook elements are formed in the hollow spaces in such a manner that thethermoplastic synthetic resin hardens at least partially in the hollowspaces of the screen.

The formation of the hook elements using two screens engaging on oneanother advantageously permits producing very finely structured hookelements, as they are provided in the micro-adhesive closing elements(see DE 196 46 318 A1), at low cost. The second interior screen engagingon the exterior screen involves an additional forming element during theforming of the rod forming the hook elements, and also involving its endconfiguration.

In this manner, the advantage is obtained that no particularrequirements need be met concerning the geometry of the openings of thescreen, because the shape and condition of the enlarged end area of therod formed by the filled-in synthetic resin are obtained exclusivelythrough the hollow spaces of the interior screen. The diameter of theinterior screen hollow spaces is selected to be somewhat greater thanthe diameter of the hollow spaces of the exterior screen. Thedifferential in diameter is selected so that the withdrawal of the rodcan take place with the end enlargement formed by a hollow space of theinterior screen and can occur following hardening or partial hardeningof the synthetic resin without any difficulties. Costly processing forthe formation rounded edges is not required around the hollow spaces ofthe interior screen or around the hollow spaces of the exterior screen.

The method according to the present invention can be carried out in sucha manner that the hook connection effect of the adhesive closing elementis almost identical on the two sides. For this purpose, the hookelements of both sides can be configured to be identical, in terms ofboth their packing density and also their geometry and dimensions. Suchan adhesive closing element is suitable particularly for the formationof secure, permanent hooking on two sides.

Adhesive closing elements can have different adhesive properties on thetwo sides as a result of different packing densities, form design and/ordimensions of the hook elements on the two sides. These closing elementscan preferably be used for detachment of the hooking connection limitedto only one side. This arrangement, for example, is advantageous in thecase of carpet-laying systems.

Other objects, advantages and salient features of the present inventionwill become apparent from the following detailed description, which,taken in conjunction with the annexed drawings, discloses preferredembodiments of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring to the drawings which form a part of this disclosure:

FIG. 1 is a diagrammatic, simplified partial side elevational view insection of a device for performing the method according to the presentinvention;

FIG. 2 is a perspective view of two screens fitted into one another withhollow spaces formed by the screen openings shown in exaggeratedmagnitudes in certain areas for clarity, of the device of FIG. 1;

FIG. 3 is a diagrammatical, simplified front elevational views insection of the segment of a forming element with screens fitting intoone another according to FIG. 2, and

FIGS. 3a-3 c are three enlarged side elevational views in section ofdifferent shapes of hollow spaces formed by the screen openings of thescreens which are fitted into one another of FIG. 2, according to threedifferent embodiments of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows elements of a device for performing the method according tothe present invention having an extruder head 1 as a feed device to feedthermoplastic synthetic resin in a plastic or fluid state. The plasticis extruded as a strip whose width corresponds to that of the adhesiveclosing element to be produced. The strip is fed into the gap betweenmovable forming tools, indicated in their entirety as 5. The two formingelements 5 are driven or rotated in the direction of rotation as shownin FIG. 1 by curved arrows 7 and 9. A conveyance gap is formed betweenforming elements 5 through which the plastic strip is conveyed in thedirection of conveyance. Simultaneously, in the gap, the plastic stripis formed into the support 17 of the adhesive closing element. Thesupport 17 engages forming elements 5 on both of its sides. By means ofthe forming elements 5, the extruded plastic attains he shaping requiredfor the formation of hook elements.

For shaping the hook elements, the two forming elements S have aroundeach of their peripheries two shaping elements, each in the form of ascreen. An exterior screen 11 and an interior screen 13 engage on oneanother, as shown in FIG. 2. As is particularly exhibited in FIG. 3,screens 11 and 13 are fitted into one another in such a manner that thebollow spaces 12 and 14 formed by the screen openings of exterior screen11 and interior screen 13 are aligned with one another and have onecommon axis 15, see particularly FIG. 3a.

As shown in FIGS. 3 and 3a-c, exterior screen 11 has a greater thicknessthan that of interior screen 13. The interior screen hollow spaces 14have a greater cross-sectional diameter or dimension that the hollowspaces 12 of exterior screen 1l. Because of this configuration, theplastic in the gap between forming elements 5 and pressed into thehollow spaces 12 and 14 is formed so that both sides of support 17 areformed with projecting rods 19 with enlarged ends 21. The differencebetween the cross sectional dimensions of hollow spaces 12 and 14 isselected so that the enlargement at end 21 is only of sufficientdimensions that withdrawal of rod 19 from hollow spaces 12, and 14 canstill certainly occur following partial or complete hardening of theplastic, when support 17 is conducted away from bottom forming element 5over a withdrawal roll 23.

FIGS. 3a to 3 c show shapes of the screen openings forming hollow spaces12 and 14 that can be selected to be different from one another. Asshown in FIG. 3a, the shapes require no rounding of the edges. Roundingcan however, as shown in FIGS. 3b and 3 c, be provided on the exteriorscreen 11 either on the exterior side or on both sides, respectively.Also interior screen 13 could correspondingly have roundings of itsopenings. In a different embodiment from FIG. 3, screens 11 and 13 couldbe of identical thickness. A precise positioning of screens 11 and 13relative to one another can be obtained by application of adhesivebefore the withdrawal on the already cooled forming elements 5, forexample by means of a two-component adhesive.

While various embodiments have been chosen to illustrate the invention,it will be understood by those skilled in the art tat various changesand modifications can be made therein without departing from the scopeof the invention as defined in the appended claims.

What is claimed is:
 1. A method for producing an adhesive closingelement having a plurality of hook elements configured unitarily as onepiece on a support and having the hook elements being rods with endenlargements, comprising the steps of: feeding thermoplastic syntheticresin in a plastic or fluid state into a gap between movable tools;driving the tools to form the support in the gap and to convey thesupport in one direction; forming the hook elements on both sides of thesupport by forming elements operating on both sides of the gap, theforming elements including first and second screens with first andsecond hollow spaces, respectively, passing entirely therethrough, thesecond screen being arranged on an interior of the first screen; andhardening the thermoplastic synthetic resin at least partially in thehollow spaces of the screens.
 2. A method according to claim 1 whereineach of the tools comprises the first and second screens driven throughthe gap through which the support is moved.
 3. A method according toclaim 2 wherein the forming elements are tempered.
 4. A method accordingto claim 1 wherein the second hollow spaces have larger cross-sectionaldimensions than the first hollow spaces.
 5. A method according to claim4 wherein the screens have hollow spaces of different dimensions.
 6. Amethod according to claim 5 wherein the hollow spaces havecross-sectional forms deviating from circles.
 7. A method according toclaim 4 wherein the hollow spaces have cross-sectional forms deviatingfrom circles.
 8. A method according to claim 4 wherein the first andsecond screens have different thicknesses.
 9. A method according toclaim 8 wherein the second screen is thinner than the first screen. 10.A method according to claim 1 wherein the first and second screens havedifferent thicknesses.
 11. A method according to claim 10 wherein thesecond screen is thinner than the first screen.
 12. A method accordingto claim 1 wherein downstream of the gap and releasing of the rods fromthe forming elements, ends of the rods are deformed to produce the endenlargements.
 13. A method according to claim 1 wherein thethermoplastic synthetic resin is a polyolefin.
 14. A method according toclaim 1 wherein the thermoplastic synthetic resin is a blend ofpolyamides.
 15. A method according to claim 1 wherein respective firstand second hollow spaces are coaxially aligned.
 16. A method accordingto claim 1 wherein said screens are concentric cylinders.